This invention relates to feed hoppers for bulk items and especially to feed hoppers for feeding pellet-like items to a conveyor in a controlled manner.
In the manufacture of many pharmaceutical products such as pills or lozenges, candies such as xe2x80x9cMIM""s(copyright)xe2x80x9d and small mechanical parts, it is often desirable to imprint a trademark, indicia or other information or intelligence on each item. These products share a common characteristic in that they are all pellet-like, being small, often round or rounded, oval, bulbous, cylindrical or polygonal in shape. Examples of pellet-like items are pills, lozenges, capsules, tablets and caplets.
Imprinting indicia on a series of pellet-like items is conveniently accomplished by a machine which receives a large number of items in bulk, typically from a feed hopper or bin, orients the items to a uniform relative orientation, conveys the oriented items to a printing unit wherein the indicia are applied to each item and discharges the items for subsequent packaging. U.S. Pat. No. 2,859,689 to Ackley is a typical example of a pellet-marking machine which performs the steps outlined above. Pellet-like items, seen in FIG. 2 of the ""689 patent, designated xe2x80x9cPxe2x80x9d, are loaded in bulk into the feed hopper 22 where the items are received by a rotating drum or cylinder roll 23. The drum has a multiplicity of concavities or recesses 33 in its outwardly facing surface formed in accordance with the shape and size of the pellet-like items being processed. The items P are received into the concavities 33 as the drum rotates clockwise beneath hopper 22, retained in the concavities by cylindrical retainer surface 50 as the drum rotates and released to an endless conveyor 24 located beneath the drum, the conveyor having a multiplicity of individual carrier bars 110. Carrier bars 110 have corresponding concavities matching the concavities 33 in drum 23, and conveyor 24 is synchronized with drum 23 so that the matching concavities on the drum and the conveyor line up as the drum rotates clockwise and the conveyor circulates counterclockwise. Items P drop from concavities 33 in drum 23 into the matching concavities in the endless conveyor 24 once the items are clear of retaining surface 50. The pellet-like items P are then conveyed to a printing roller 27 which has ink laden images of the indicia or intelligence to be imprinted on the items circumferentially arrayed on its peripheral surface. Printing roller 27 rotates clockwise in synchronization with endless conveyor 24 and contacts the pellet-like items P as they pass beneath the printing roller 27, applying the ink laden image to each pellet-like item. After passing beneath printing roller 27 the pellet-like items P are discharged from conveyor 24 as the conveyor rounds its drive sprocket and the carrier bars 110 are momentarily vertically oriented.
Using a rotating drum to effect the orderly transfer of pellet-like items from the feed hopper to the conveyor avoids overburdening the conveyor with the weight of all of the items in the feed hopper, as the drum bears this weight. However, the rotating drum has numerous disadvantages. The drum is an expensive and massive part of the machine which must be strong enough to withstand the weight of the items in the feed hopper. This increases the machine cost and weight. The drum is a moving part, the rotation of which must be synchronized with the conveyor motion, thus, increasing the machine complexity. Close tolerances must be maintained between the drum and the retaining surface to keep the items in place, and pellet-like items which are not properly seated within the cavities tend to be pinched and crushed between the drum and the surface due to the close tolerances. This is especially messy when liquid filled capsules are being processed, because the liquid from crushed capsules contaminates the drum surface and coats capsules contacted by the drum unless the machine is shut down and the liquid cleaned up. This results in significant machine down time and unacceptable loss of product throughput. Furthermore, the drum inherently limits the speed at which the machine can process items, because the drum itself cannot rotate above a critical speed at which the pellet-like items either fail to seat properly within the cavities or are flung outwardly from the hopper under the centrifugal acceleration of the spinning drum.
Clearly, it is, therefore, perceived that there is need for an improved machine for processing pellet-like items which eliminates the aforementioned disadvantages inherent in the drum machine yet provides for the orderly transfer of pellet-like items from the feed hopper to the conveyor without placing the bulk of the weight of the items directly on the conveyor.
The invention concerns a feed hopper adapted to receive a multiplicity of pellet-like items and discharge the items on a movable conveyor. Preferably, the feed hopper comprises a chamber enclosed by a plurality of side walls, the chamber having a top opening for receiving the pellet-like items and a bottom opening positioned overlying the conveyor. According to the invention, a plurality of baffle plates are arranged within the chamber in spaced relationship one above another. The baffle plates extend partially across chamber to deflect the pellet-like items along an indirect path from the top opening to the conveyor. When pellet-like items are introduced into the hopper through the top opening, they impact on at least one of the baffle plates. The baffle plates impede the flow of the pellet-like items through the hopper before they land on the conveyor. One of the chamber side walls is arranged substantially transversely to the direction of motion of the conveyor, the one side wall having an opening positioned adjacent to the conveyor. When the conveyor moves, the pellet-like items on the conveyor are discharged from the chamber through the opening.
The feed hopper preferably has first and second oppositely arranged side walls disposed transversely to the direction of motion of the conveyor, one of the side walls having the above mentioned opening through which the pellet-like items are discharged. At least one baffle plate is positioned within the chamber with a first edge adjacent to the first side wall and a second edge arranged distally to the first edge and extending toward the second, opposite side wall. At least another baffle plate is arranged having a first edge adjacent to the second side wall and a second edge arranged distally to the first edge and extending toward the first side wall. Both baffle plates are inclined at an angle by arranging the second edge at a lower level than the first edge for each respective baffle plate.
The two baffle plates described above are preferably arranged vertically adjacent one above another, with no other baffle plates in between. One of the baffle plates is movable between an open position in spaced relation to the other baffle plate, and a closed position wherein the second edge of the one baffle plate is contiguous with the second edge of the other baffle plate thereby closing off the chamber and preventing movement of the pellet-like items through the hopper to the conveyor. In the preferred embodiment, the lower of the two baffle plates is rotatably movable between the open and closed positions to effect the closure of the chamber, and this movable baffle plate is positioned lowermost of all the baffle plates within the chamber.
As noted above, it is desirable not to overload the conveyor with an excessive amount of pellet-like items. The conveyor is not designed to bear the full weight of product which can be loaded into the hopper. Therefore, it is convenient to associate with the hopper a means for measuring the quantity of the pellet-like items received on the conveyor and a means for moving the first baffle plate between the open and the closed positions, and a means for controlling the moving means in response to the quantity of pellet-like items measured.
The controlling means causes the moving means to move the first baffle plate from the open to the closed position when the quantity measured exceeds a first predetermined amount. This prevents further of the pellet-like items from being received on the conveyor. The controlling means also causes the moving means to move the first baffle plate from the closed to the open position when the quantity measured is less than a second predetermined amount which is also less than the first predetermined amount. This allows further of the pellet-like items to be received on said conveyor.
In the preferred embodiment, the measuring means comprises a light source mounted within the chamber. The light source projects a light beam across the chamber at a predetermined level above the conveyor to a light sensor also mounted within the chamber, facing the light source and aligned to receive the beam. The light beam projects unimpeded across the chamber from the light source to the light sensor when the pellet-like items received on the conveyor are below the level of the light beam. This level of pellet-like items corresponds to an acceptable amount of product on the conveyor, and the moveable baffle plate remains in the open position allowing items to pass from the hopper to the conveyor. However, the light beam is interrupted by the pellet-like items received on the conveyor when the pellet-like items are above the level of the light beam. This corresponds to near an unacceptable amount of items on the conveyor and exceeds the predetermined amount allowed on the conveyor. Interruption of the light beam triggers, via the controlling means, the movement of the movable baffle plate to the closed position which prevents further pellet-like items from reaching the conveyor. As the conveyor moves the pellet-like items from the hopper, the level of the items decreases and the light beam again projects unimpeded from the source to the sensor. Resumption of the light beam being sensed by the sensor triggers the movement of the baffle plate to the open position allowing pellet-like items to flow through the hopper to the conveyor.
For delicate or brittle items, it is sometimes necessary to mitigate or soften the impact of the item on the baffle plates. This is accomplished by providing the upwardly facing surface of the baffle plates with a layer of flexible material cushioning the impact of the pellet-like items on the baffle plates.
In machines where the conveyor has carrier bars having a multiplicity of cavities for receiving and transporting the pellet-like items, the hopper is equipped with a guard member. The guard member extends substantially transversely to the direction of motion of the conveyor and is positioned adjacent to the opening discharging the items. The guard member engages a first portion of the pellet-like items which are not received within the cavities and retains this first portion within the chamber when the conveyor is moving. A second portion of the pellet-like items which are properly received in the cavities are not retained by the guard member and are discharged through the opening and out of the chamber on the conveyor.
In the preferred embodiment, the guard member is an elongated rotatable brush having a multiplicity of flexible bristles extending radially outwardly. The brush is rotatable about an axis arranged substantially transversely to the direction of motion of the conveyor and means for rotating the brush, such as an electric motor, are operatively connected to the brush. The brush is rotated in opposition to the motion of the conveyor and the bristles engage the conveyor and sweep the first portion of pellet-like items (those items not arranged within the cavities of the conveyor) back into the chamber. The second portion of the pellet-like items received in the cavities are not swept back but bypass the brush and are transported through the opening and discharged from the chamber on the conveyor.
Pellet-like items falling through the hopper onto the carrier bars of the conveyor are randomly oriented and do not automatically align themselves and seat within the cavities in the carrier bars. To encourage the proper alignment of the pellet-like items, the hopper is fitted with at least two elongated guide bars mounted within the chamber. The guide bars are arranged parallel to the direction of motion of the conveyor and positioned in spaced relationship to each other on opposite sides of one of the cavities, thereby forming a trough for guiding the pellet-like items into the cavity.
The invention also includes a method of loading a movable conveyor with a multiplicity of pellet-like items. The method comprises the steps of:
(A) positioning a feed hopper above the conveyor, the feed hopper comprising a chamber having a top opening and a bottom opening overlying the conveyor;
(B) providing a plurality of baffle plates within the chamber, the baffle plates being angularly oriented with respect to the horizontal one above another and extending partially across the chamber;
(C) providing an opening in the chamber adjacent to the conveyor and transversely to the direction of motion of the conveyor;
(D) introducing the pellet-like items into the chamber through the top opening, the items passing through the chamber under gravity and contacting at least one of the baffle plates before emerging from the bottom opening onto the conveyor, the baffle plates impeding the flow of the pellet-like items from the hopper to the conveyor; and
(E) moving the pellet-like items on said conveyor from beneath said hopper through said opening.
It is desirable to include in the method further steps to control the flow of pellet-like items through the chamber so as to avoid overloading the conveyor. The further steps comprise:
(F) providing a means for measuring a quantity of the pellet-like items on the conveyor;
(G) providing a baffle plate movable between an open position allowing the pellet-like items to move through the chamber to a closed position blocking the chamber between the top and the bottom openings;
(H) providing a means for moving the baffle plate in cooperation with the measuring means;
(I) providing a means for controlling the moving means in response to the quantity measured by said measuring means;
(J) measuring the quantity of pellet-like items on the conveyor;
(K) moving the movable baffle plate into the closed position when the quantity exceeds a first predetermined amount, thereby halting the flow of the pellet-like items through the hopper onto the conveyor; and
(L) moving the movable baffle plate into the open position when the quantity is less than a second predetermined amount less than the first predetermined amount, thereby permitting the flow of the pellet-like items through the hopper.
It is an object of the invention to provide a feed hopper for loading a plurality of pellet-like items onto a conveyor.
It is another object of the invention to provide a feed hopper which provides for the orderly transfer of pellet-like items to the conveyor.
It is still another object of the invention to provide a feed hopper which eliminates the need for a rotating drum in pellet-marking machines.
A further object of the invention is to provide a feed hopper which controls the flow of pellet-like items onto the conveyor.
The objects of the invention include the provision of a feed hopper which prevents the pellet-like items from being deposited directly onto the conveyor.
The objects of the invention further include the provision of a feed hopper which prevents the full weight of pellet-like items in the hopper from being supported on the conveyor.
These and other objects can be discerned from a consideration of the following drawings and detailed description of the invention.